'''
Middleware for the church_db project.
'''

#------------------------------------------------------------------------------
# Base template for the html/url locator comment block
COMMENT_BLOCK = """
<!--
[ url      ] >> http://%(host)s%(path)s
[ referer  ] >> %(referer)s
[ module   ] >> %(module)s
[ function ] >> %(function)s, line %(line)s
[ args     ] >> args=%(args)s, kwargs=%(kwargs)s, defaults=%(defaults)s
[ template ] >> %(template)s
-->

"""

# Add any additional template types you wish to add the comment block to.
MIMETYPES = (
    "text/html",
    "text/xml",
)


class HtmlTemplateFinder:
    """
    Middleware class that adds a comment block to an html response object.
    Currently adds url, referer, the python module and its function/line,
    the function arguments, and the template passed in. Only triggers if
    a SimpleTemplateResponse object was used to render the template and
    the template is .html.
    """

    def __init__(self):
        self.host = None
        self.referer = None
        self.path = None
        self.module = None
        self.function = None
        self.line = None
        self.args = None
        self.kwargs = None
        self.defaults = None
        self.template = None
        self.valid_template = False

    def _populate_comment_block(self):
        return COMMENT_BLOCK % {
                                'host': self.host,
                                'referer': self.referer,
                                'path': self.path,
                                'module': self.module,
                                'function': self.function,
                                'line': self.line,
                                'args': self.args,
                                'kwargs': self.kwargs,
                                'defaults': self.defaults,
                                'template': self.template,
                               }

    def process_view(self, request, view_func, view_args, view_kwargs):
        self.host = request.META.get('HTTP_HOST', None)
        self.referer = request.META.get('HTTP_REFERER', None)
        self.path = request.path
        self.module = view_func.func_code.co_filename
        self.function = ('.').join((view_func.__module__, view_func.func_name))
        self.line = view_func.func_code.co_firstlineno
        self.args = view_args
        self.kwargs = view_kwargs
        self.defaults = view_func.func_defaults
        return None

    def process_template_response(self, request, response):
        from mimetypes import guess_type
        # Use this rather than response.template_name, this always returns str
        self.template = response.resolve_template(response.template_name).name
        self.valid_template = guess_type(self.template)[0] in MIMETYPES
        return response

    def process_response(self, request, response):
        from church_db import settings
        if settings.DEBUG:
            if self.valid_template:
                block = self._populate_comment_block()
                response.content = "%s%s" % (block, response.content)
        return response
